Radio frequency identification (RFID) transponders or tags are well known and come in a wide variety of shapes and sizes. They can be as small as a pencil lead in diameter and one-half inch in length. They can be credit-card shaped for combined use with barcode visual inspection applications. RFID tags can also be used for inventory and security purposes. For example, the anti-theft hard plastic tags attached to merchandise in stores are RFID tags.
RFID tags are categorized as either active or passive. Active RFID tags are powered by an internal battery and are typically read/write, i.e., tag data can be rewritten and/or modified, and typically last up to four years. However, active tags are less desirable in many applications due to their cost, size, and longevity limitations.
Passive RFID tags operate without a separate external power source and obtain operating power from a reader. Passive tags are consequently much lighter than active tags, less expensive, and offer a virtually unlimited operational lifetime. Read-only tags are typically passive and generally are programmed with a unique set of data (usually 32 to 128 bits) that cannot be modified.
RFID-based designs provide for noncontact, non-line-of-sight sensing. Tags can be employed by a vendor for different purposes during the entire life-cycle of the equipment, from manufacturing to distribution to sales to deployment to services and finally disposal. Tags can be employed by the customers for a wide range of purposes as well, including site capacity planning, asset management, and protection.
Determining an individual user's presence is vital for the growing adoption of realtime communications. Existing methods rely upon direct user interaction with an input device, such as a keyboard or mouse, to determine a user's status, i.e., if a user is online or away from his computer. Computers, devices, and other resources that may be used by an individual or group of individuals are generally not able to recognize the presence of a user or group of users without such direct interaction. Thus, although a user may be near his device such as a computer, if he is not actively directly interacting with it (e.g., by pressing a key or moving a pointer) within a certain predetermined time period, the device may go into a power saving mode (e.g., blank the screen), log the user out, or otherwise prohibit the user from immediately accessing the system. This is undesirable if, for example, the user is present and would like the device to remain in the normal operating mode although he is not directly interacting with it.
Similarly, in a conventional system, if a user directly interacts with the device and then, for example, leaves the room, the device typically remains powered on in the regular operating mode for a predetermined time. This is a security concern, as another user could enter the room and access the computer, although he may not be authorized to do so. Moreover, energy is wasted if the device remains powered on in the regular operating mode for a predetermined time after a user leaves the room.
In view of the foregoing, there is a need for systems and methods that overcome the limitations and drawbacks of the prior art.